JP2005510990A - Multi-directional thermal actuator - Google Patents

Abstract

  A micrometer-sized multi-directional thermal actuator that can be repeatedly and rapidly displaced in a substantially horizontal direction, a substantially vertical direction, and / or a combination thereof. The multi-directional thermal actuator constructed on the surface of the substrate has three or more beams each cantilevered from one or more anchors at the first end so as to extend substantially parallel to the surface of the substrate. Is provided. A member mechanically and electrically couples the distal end of the beam. By applying an electric current to a circuit comprising a combination of any two or more of the beams, the members are each displaced in one of three or more non-parallel radial directions.

Description

  The present invention generally relates to micromechanical devices, and more specifically, can traverse a substrate horizontally, move away from the surface of the substrate vertically, or a combination thereof to repeatedly move quickly. The present invention relates to a micrometer-sized thermal actuator that can be used.

  The manufacture of complex microelectromechanical system (MEMS) and microoptical electromechanical system (MOEMS) devices represents a significant advance in micromechanical device technology. Currently, micrometer-sized analogs have been created for many macroscale devices such as hinges, shutters, lenses, mirrors, switches, polarizers, and actuators. These devices are, for example, multi-user MEMS processing (MUMP) available from Cronos Integrated Microsystems (Research Triangle Park, North Carolina) in Research Triangle Park, North Carolina. Can be manufactured using. Application examples of MEMS and MOEMS devices include data storage devices, laser scanners, printer heads, magnetic heads, micro-spectrometers, accelerometers, scanning exploration microscopes, near-field optical microscopes, optical scanners, light modulators, These include microlenses, optical switches, and microrobot engineering.

  One method of forming a MEMS or MOEMS device involves patterning the device at an appropriate location on a substrate. When patterned, the device lies flat on the substrate. For example, the hinge structure or the hinge plate of the reflector device are both formed to be substantially coplanar with the surface of the substrate using the MUMP process. One challenge in using these devices is to move the device out of the plane of the substrate.

  Coupling the actuators with the micromechanical devices allows for moving these devices out of the plane of the substrate. Various types of actuators have been used for this purpose, including electrostatic, piezoelectric, thermal, and magnetic.

  One such actuator is described by Cowan et al. In “Vertical Thermal Actuator for Micro-Opto-Electro-Mechanical Systems” v. 3226, SPIE, pages 137-146 (1997). The Cowan et al. Actuator 20 shown in FIG. 1 uses resistive heating to induce thermal expansion. The hot arm 22 is higher than the cantilever arm 24 and, therefore, due to thermal expansion, the actuator tip 26 is pushed toward the surface of the substrate 28. At a sufficiently large current, the downward deflection of the actuator tip 26 is stopped by contacting the substrate 28 and the hot arm 22 curves upward. In removing the drive current, the hot arm 22 rapidly “freezes” and contracts in a curved shape, as shown in FIG. 2, pulling the actuator tip 26 upward.

  The deformation of the hot arm 22 is permanent and the actuator tip 26 remains deflected upward without applying force, forming a backbend actuator 32. By further applying drive current, the backbend actuator 32 rotates in a direction 30 toward the surface of the substrate 28. The backbend actuator 32 of FIG. 2 is typically used for setup or one-time positioning applications. The actuator described in Cowan et al. Is limited in that the hinge plate cannot be rotated or raised out of plane well beyond 45 degrees in a single operating step.

  Hirsch (Harsh) et al., "Flip Chip Assembly for Si-Based Rf MEMS", Technical Digest of the Twelfth IEEE International Conference on Micro Electro Mechanical Systems, IEEE Microwave Theory and Techniques Society 1999,273~278 page; Hirsch (Harsh) et al. "The Realization and Design Condenses of aFlip-Chip Integrated MEMS Tunable Capacitor", 80 Sensors and Actuators, 10 -118 pages (2000); and Feng et al., "MEMS-Based Variable Capacitor for Millimeter-Wave Applications," Solid-State Sensor and Actor work in Ireland, H. 2000, pages 225-258, describes various vertical actuators based on flip-chip designs. During the normal release etch step, the base oxide layer partially dissolves and the remaining MEMS components are released. The ceramic substrate is then bonded to the exposed surface of the MEMS device and the base polysilicon layer is removed by completing the etching of the base oxide layer (ie, a flip-flop process). The resulting device is a capacitor without any polysilicon substrate, and the top plate of the capacitor can be controlled to move downward toward the opposing plate on the ceramic substrate. The device has the polysilicon substrate removed because the effects of the stray capacitance of the polysilicon layer, at a minimum, interfere with the operation of the device.

  A lift angle significantly greater than 45 degrees can be achieved with a two-stage actuator system. A two-stage actuator system usually consists of a vertical actuator and a motor. The vertical actuator raises the hinge micromechanical device from the substrate to a maximum angle not significantly greater than 45 degrees. The motor has a drive arm connected to the lift arm of the micromechanical device to achieve the lift. One such two-step assembly system is described by Reid et al., “Automated Assembly of Flip-Up Micromirrors”, Transducers'97, Int'l Conf. Solid-State Sensors and Actuators, pages 347-350 (1997). These two-stage actuators are typically used for setup or one-time positioning applications.

  The present invention relates to a micrometer sized multi-directional thermal actuator that can be repeatedly and rapidly displaced in a substantially horizontal direction, a substantially vertical direction, and combinations thereof. In some embodiments, the thermal actuator can be displaced radially in virtually any direction with respect to the inactive position. In this case, the radial direction refers to a direction perpendicular to the longitudinal axis of the beam.

  In one embodiment, the multi-directional thermal actuator constructed on the surface of the substrate is first cantilevered from an anchor at a first end so as to extend substantially parallel to the surface of the substrate in an inactive configuration. Includes a beam, a second beam, and a third beam. The first beam, the second beam, and the third beam are not coplanar. A member mechanically couples the distal ends of the first beam, the second beam, and the third beam. The first circuit includes at least a first beam, and thereby applying a current to the first circuit displaces the member in the first radial direction. The second circuit comprises at least a second beam, whereby the member is displaced in the second radial direction by applying a current to the second circuit. The third circuit comprises at least a third beam, whereby the member is displaced in the third radial direction by applying a current to the third circuit.

  In one embodiment, a ground tab electrically couples one or more of the beams to the substrate. A resistor can be arbitrarily placed between one or more of the beams and the ground. In one embodiment, the first beam and the second beam comprise a first circuit, the second beam and the third beam comprise a second circuit, and the third beam and the first beam comprise a third circuit. In other embodiments, the first beam and ground tab comprise a fourth circuit, the second beam and ground tab comprise a fifth circuit, and the third beam and ground tab comprise a sixth circuit. The same or different levels of current can be applied simultaneously to one or more of the circuits. The first beam, the second beam, and the third beam can be arranged in a symmetric or asymmetric cross-sectional configuration.

  Other embodiments include a fourth beam that is cantilevered from the anchor at the first end so as to extend substantially parallel to the surface of the substrate in an inactive configuration. The fourth beam is mechanically coupled to the member.

  In the fourth beam embodiment, the first beam and the fourth beam comprise a seventh circuit, whereby the member is displaced in the seventh radial direction by applying a current to the seventh circuit. The second beam and the fourth beam are provided with an eighth circuit, whereby the member is displaced in the eighth radial direction by applying a current to the eighth circuit. The third beam and the fourth beam are provided with a ninth circuit, whereby the member is displaced in the ninth radial direction by applying a current to the ninth circuit. The first beam, the second beam, the third and fourth beams can be arranged in a symmetric or asymmetric cross-sectional configuration.

  In some embodiments, the multi-directional thermal actuator includes a cold arm having a first end secured to the surface of the substrate and a distal end mechanically coupled to the member. The beams can be arranged symmetrically or asymmetrically with respect to the cold arm.

  The present invention also comprises at least three beams that are cantilevered from one or more anchors at the first end such that each beam extends substantially parallel to the surface of the substrate in an inactive configuration, It also covers multi-directional thermal actuators built on the surface of the substrate where at least one of the beams is not coplanar with the other two beams. The member mechanically and electrically couples the distal end of the beam, thereby applying a current to a circuit comprising a combination of any two or more beams so that the member is not more than two in parallel. Displacement in each of the non-radial directions.

  In one embodiment, multi-directional thermal actuators built on the surface of the substrate were cantilevered from one or more anchors at the first end such that each extends substantially parallel to the surface of the substrate. Two lower hot arms and two upper hot arms cantilevered from one or more anchors at a first end such that each extends substantially parallel to the surface of the substrate. The two upper hot arms are each positioned above the two lower hot arms. A member mechanically and electrically couples the far end of the upper and lower hot arms.

  The actuator exhibits a vertical displacement when current is applied to the two lower hot arms or the two upper hot arms. The actuator exhibits a horizontal displacement when current is applied to one of the lower hot arm and the upper hot arm positioned above the lower hot arm. The actuator exhibits both horizontal and vertical displacement when current is applied to any three of the hot arms.

  In one embodiment, a cold arm having a first end and a distal end secured to the surface of the substrate is disposed generally parallel to the upper and lower hot arms. The cold arm is preferably arranged symmetrically with respect to the hot arm. In one embodiment, the cold arm is centrally located in a generally rectangular space defined by an upper hot arm and a lower hot arm. A deflection is optionally formed in the cold arm near its first end. Deflections include depressions, depressions, cutouts, holes, material narrow, thin, or weak locations, alternative materials or other structural features, or material changes that reduce resistance to curvature at those locations. And at least one. In other embodiments, the cold arm includes a reinforcing member. The reinforcing member can be integrally formed in the cold arm. The metal layer optionally extends along the cold arm to reduce the current density.

  In one embodiment, the cold arm is electrically isolated from the hot arm. In other embodiments, the hot arm and cold arm comprise circuitry through which current can flow. Actuators are designed for horizontal displacement and vertical displacement when current is applied to a circuit with one of the cold and hot arms, three of the hot arms, or two unbalanced sets of arms. It exhibits both displacements. A ground tab can optionally be provided to electrically couple one or more of the hot arms to the substrate.

  Multiple multi-directional thermal actuators can be formed on a single substrate. At least one optical device may be mechanically coupled to the multidirectional thermal actuator. The optical device comprises one of a reflector, lens, polarizer, waveguide, shutter, or engagement structure. The present invention is also directed to an optical communication system including at least one optical device.

  The present invention relates to multi-directional thermal actuators for micromechanical devices. Micrometer-sized multi-directional thermal actuators can be moved quickly and repeatedly in a substantially horizontal direction, in a substantially vertical direction from a surface, or a combination thereof. The multi-directional thermal actuator of the present invention can be designed to have one or more preferred directions of radial displacement.

  As used herein, “micromechanical device” refers to a micrometer-sized mechanical, optomechanical, electromechanical, or optoelectromechanical device built on the surface of a substrate. A variety of micro-machinery fabrication technologies are used, such as Cronos Integrated Microsystems, Research Triangle Park, North Carolina's Multi-User MEMS Processing (MUMP) at Research Triangle Park, North Carolina Is possible. One description of the assembly procedure is described in “MUMPs Design Hadbook” revision 6.0, (2001), available from Cronos Integrated Microsystems.

  With polysilicon surface micromachining, planar fabrication process steps known in the integrated circuit (IC) industry are adapted to fabricate microelectromechanical devices or micromechanical devices. The standard building block process for polysilicon surface micromachining is the deposition of alternative layers of low stress polycrystalline silicon (also called polysilicon) and sacrificial material (such as silicon dioxide or silicate glass) and photolithographic patterning It is. Vias etched through the sacrificial layer in place provide anchor points to the substrate and provide mechanical and electrical interconnections between the polysilicon layers. The functional elements of the device are built layer by layer using a series of deposition and patterning process steps. After the device structure is completed, the device structure can be released to move by removing the sacrificial material using a selected etchant such as hydrofluoric acid that does not significantly affect the polysilicon layer. .

  As a result, it can generally be used to form a first layer of polysilicon that provides electrical interconnection and / or voltage reference planes and functional elements ranging from simple cantilevers to complex electromechanical systems. A structural system comprising an additional layer of mechanical polysilicon. The entire structure is placed in-plane with respect to the substrate. As used herein, the term “in-plane” refers to a configuration that is substantially parallel to the surface of the substrate, and the term “out-of-plane” is up to about 90 degrees greater than zero degrees relative to the surface of the substrate. Refers to the configuration.

  Typical in-plane lateral dimensions of the functional elements can range from 1 micrometer to several hundred micrometers, while the layer thickness is typically about 1-2 micrometers. Since the entire process is based on standard IC fabrication techniques, a large number of fully assembled devices can be fabricated in bulk on a silicon substrate without the need for component assemblies.

  3-5 illustrate a first embodiment of a multi-directional thermal actuator 50 constructed on a substrate 52 according to the present invention. Multidirectional thermal actuator 50 is oriented in-plane on the surface of substrate 52. The substrate 52 typically comprises a silicon wafer having a layer having silicon nitride deposited thereon. As used herein, the term “multidirectional thermal actuator” refers to a micromechanical device that can be repeatedly moved substantially horizontally across a substrate, substantially perpendicularly from the substrate, or a combination thereof. A multidirectional thermal actuator can optionally have one or more preferred directions of radial displacement. The force generated in the preferred direction of radial displacement is usually greater than the force generated in the other direction of curvature. Multidirectional thermal actuators typically have greater stiffness or resistance to bending in directions other than the preferred direction of radial displacement.

  The multi-directional thermal actuator 50 includes an anchor 54 having a first lower beam 56 extending from the anchor 54 in a cantilever manner and a second lower portion extending from the anchor 58 in a cantilever manner substantially parallel to the first lower beam 56. And an anchor 58 having a beam 60. Anchor 62 includes a first upper beam 64 extending therefrom in a cantilever manner and an anchor 66 having a second upper beam 68 extending in a cantilever manner substantially parallel to the first upper beam 64. In alternative embodiments, two or more of the beams 56, 60, 64, 68 can be cantilevered from the same anchor, but need not be electrically isolated from each other.

  As best shown in FIG. 5, the beams 56, 60, 64, 68 are configured in a generally rectangular cross-sectional configuration (see also FIG. 8). As used herein, “cross-sectional configuration” refers to a cross-sectional view taken perpendicular to the longitudinal axis of the beam, usually near the distal end. The cross-sectional configuration can be symmetric or asymmetric. Examples of rectangular cross-sectional configurations can be seen in FIGS. Examples of symmetrical cross-sectional configurations can be seen in FIGS. 5 and 7-9. An asymmetric cross-sectional configuration is shown in FIG.

  In the embodiment shown in FIG. 3, the anchors 54, 58, 62, 66 are each one for delivering current and / or electrically grounding any of the beams 56, 60, 64, 68. The electrical traces 54A, 58A, 62A and 66A are connected. Traces 54A, 58A, 62A, 66A typically extend toward the edge of substrate 52. Ball grid array (BGA), land grid array (LGA), plastic lead chip carrier (PLCC), pin grid array (PGA), edge card, small integrated circuit (SOIC), double in-line package (DIP) ), A wide range of electrical contact devices and / or mounting methods such as quad flood package (QFP), leadless chip carrier (LCC), chip scale package (CSP), etc. , 62, 66 and / or beams 56, 60, 64, 68 can deliver current and / or add resistance across them.

  Various configurations can be used to change the current applied to the individual beams 56, 60, 64, 68. In one embodiment, the traces 54A, 58A, 62A, 66A have a resistance that can be applied to reduce the current density of the corresponding beams 56, 60, 64, 68. FIG. 12 schematically illustrates the anchor 66 and trace 66A of FIG. Trace 66A can optionally include a series of contacts 100, 102, 104 adapted to provide current to beam 68. The amount of current applied to the different contacts 100, 102, 104 can be different. Alternatively, current can be selectively applied to various combinations of contacts 100, 102, 104. Alternatively, contacts 100, 102, 104 may be variable resistors adapted to redirect a portion of the current in trace 66A to ground. In another embodiment shown in FIG. 13, trace 66A is replaced by a series of traces 120, 122, 124 having different widths. Current is selectively applied to contacts 100, 102, 104. However, the wider trace 124 has a smaller resistance than the narrower trace 120.

  Beams 56, 60, 64, 68 are mechanically coupled at their distal ends by members 72. A via 70 is formed in the member 72 to mechanically couple the beams 56, 60, 64, 68. Other structures can be used to mechanically couple the beams 56, 60, 64, 68 to the member 72. Some or all of the beams 56, 60, 64, 68 may be electrically coupled at the member 72 to form an electrical circuit.

  In one embodiment, any or all of the beams 56, 60, 64, 68 can be electrically coupled to the substrate 52 by ground tabs 77. A ground tab 77 electrically couples one or more of the beams 56, 60, 64, 68 to the electrical contact 79 on the substrate 52 in both a cantilever configuration and an active configuration. The ground tab 77 allows current to flow through a single beam, such as beam 56, causing member 72 to be displaced in direction 90. The ground tab 77 can be a flexible member or a spring member adapted to maintain contact with the substrate 52. A ground tab, such as tab 77, can be used with any of the embodiments disclosed herein.

  Although the embodiments of FIGS. 3-5 show the beams 56, 60, 64, 68 in substantially the same manner, the material and / or geometry of the beams 56, 60, 64, 68 can vary in current density for a given voltage. Can be adapted to have In one embodiment, some of the beams 56, 60, 64, 68 are formed from a material that has a linear coefficient of thermal expansion that is less than the linear coefficient of thermal expansion of the other beams. In other embodiments, some of the beams 56, 60, 64, 68 have a lower electrical resistance by having a larger cross-sectional area. In other embodiments, conductive layers are provided on some of the beams 56, 60, 64, 68. Suitable conductive materials include metals such as aluminum, copper, tungsten, gold, or silver, semiconductors, and doped organic conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyEDOT, and derivatives or combinations thereof. As a result, the net expansion of the beams 56, 60, 64, 68 for a given level of current can be designed for a particular application.

  Another aspect of the applicable thermal actuator of the present invention is described in US application Ser. No. 09 / 659,572, entitled “Direct Acting Vertical Thermal Actuator”, filed September 12, 2000, September 12, 2000. US Application No. 09 / 659,798, filed September 12, 2000, entitled “Direct Acting Vertical Thermal Acting with Controlled Bending”, filed September 12, 2000 No. 09 / 659,282, assigned to the assignee of the present invention.

  Beams 56, 60, 64, 68 are physically separated from substrate 52 such that member 72 is located above substrate 52. In the inactive or neutral configuration shown in FIG. 4, the beams 56, 60, 64, 68 are generally parallel to the surface of the substrate 52. As used herein, “inactive configuration” refers to the potential difference between all beams being approximately zero.

  By selectively applying one or more currents in beams 56, 60, 64, 68, member 72 can be moved from the neutral or inactive configuration shown in FIG. 5 to the active configuration. “Active configuration” refers to applying sufficient current to one or more of the beams to displace member 72 from an inactive state. By selectively applying the same or different amounts of current to one or more of the beams 56, 60, 64, 68, the member 72 can be moved in any radial direction.

  One or more beams to which current is applied are “hot arms”, and beams to which no current or less current is applied are cold arms. As used herein, one or more “hot arms” refers to a beam or member that has a higher temperature than the cold arm because, when a voltage is applied, the current density is greater than the cold arm. Point to. Thus, the hot arm has a greater thermal expansion than the cold arm. One or more “cold arms” refers to a beam or member having a lower temperature due to the smaller current density of the hot arm when a voltage is applied. In some embodiments, the cold arm has a zero current density.

  A current can be applied to a circuit comprising one or more of the beams 56, 60, 64, 68. By disconnecting from ground, the current flow in one or more of the beams 56, 60, 64, 68 is substantially stopped. In a circuit with a single beam, a ground tab 77 is required to complete the circuit. By selectively applying current to the beams 56, 60, 64, 68 and / or modifying the configuration and characteristics of the beams 56, 60, 64, 68, the multi-directional thermal actuator of the present invention can be It can move in the radial direction. As used herein, “radial direction” refers to a direction substantially perpendicular to the longitudinal axis of the beam. As described below, any configuration of at least three non-coplanar arms that can selectively control current density is movable in any radial direction.

  It is also possible to change the current density of one or more beams. For example, if the circuit includes three beams, a resistor can be inserted between any of the hot arms and ground to selectively limit the current density in a particular beam. In this configuration, two of the beams have a first current density (and a first coefficient of thermal expansion) and a third beam has a second greater current density and a second (greater) coefficient of thermal expansion. Can have. In practice, the current in the third beam is divided into two beams having the first current density. In other embodiments, each of the beams typically has a different resistance due to their respective geometry. Therefore, the coefficient of thermal expansion will be different for each of the three beams.

  Alternatively, the current density can be changed in a particular beam configured to include two beams and one ground tab. For example, one beam and one ground tab can form a circuit having a first current density (and a first coefficient of thermal expansion), and the second beam has a second smaller current density and a second current density. A resistance that provides a (smaller) coefficient of thermal expansion can be included.

  In other embodiments, the ground tab comprises a resistor. For example, a circuit having a first current density (and a first coefficient of thermal expansion) can be formed with one beam and one ground tab. The second beam has a second greater current density and a second (greater) coefficient of thermal expansion.

  By selectively applying current to any two adjacent beams 56, 60, 64, 68, the member 72 moves in any of the radial directions 80, 82, 84, 86. The radial directions 82 and 84 correspond to the x-axis, and the radial directions 80 and 86 correspond to the z-axis. For example, current is applied to the beams 56, 64. The current heats the hot arms 56, 64, thereby increasing the length of the hot arms. Since the hot arms 56, 64 are laterally displaced from the cold arms 60, 68, the length of the hot arms 56, 64 increases, causing a horizontal displacement of the member 72 in the radial direction 82. Alternatively, current can be applied to the hot arms 60,68. The length of the hot arms 60, 68 increases relative to the length of the cold arms 56, 64, resulting in a horizontal displacement of the member 72 in the radial direction 84. As used herein, “horizontal displacement” refers to a displacement parallel to the plane of the substrate.

  In other examples, current is applied to the hot arms 56, 60. The length of the hot arms 56, 60 increases compared to the length of the cold arms 64, 68, resulting in a vertical displacement of the member 72 in the radial direction 80. Alternatively, the length of the hot arms 64, 68 is increased compared to the length of the cold arms 56, 60, resulting in a vertical displacement of the member 72 in the radial direction 86. As used herein, “vertical displacement” refers to displacement perpendicular to the plane of the substrate.

  In other embodiments, the multi-directional thermal actuator 50 can be continuously displaced both horizontally and vertically. For example, first, current can be applied to the hot arms 56, 60 to effect a vertical displacement of the member 72 in the radial direction 80. While current is still being applied to the hot arms 56, 60, current can also be applied to the beam 64 to displace the already vertically displaced member 72 horizontally in the radial direction 82.

  In other embodiments, the multi-directional thermal actuator 50 can be displaced simultaneously in both vertical and horizontal directions. For example, current can be applied to the three beams 56, 60, 64 to effect both vertical and horizontal displacement of the member 72 in the radial direction 90. The thermal expansion of the three beams 56, 60, 64 easily exceeds the rigidity of the cold arm 68. The displacement in direction 90 is the preferred direction of radial displacement. By applying an electrical current to any of the three combinations of beams 56, 60, 64, 68, member 72 can be displaced in any of the preferred directions of radial displacement 90, 92, 94, 96.

  In other embodiments, the level of current applied to any three of the beams 56, 60, 64, 68 can be different. For example, more current can be applied to beam 60 than beams 56 and 64 so as to displace in the region between direction 80 and direction 90. When the current is stopped, the multi-directional thermal actuator 50 returns to the original inactive configuration shown in FIGS. The factors described above can also be modified to emphasize movement in one or more directions of displacement, but not all embodiments can move in all radial directions.

  The force generated by the thermal actuator 50 is also affected by the number of beams subjected to the current, the current density of those beams, and the geometry of the beams. Displacement induced by the thermal expansion of only one beam produces a displacement force that is smaller than the displacement generated by the thermal expansion of the two beams. The displacement induced by the thermal expansion of the two beams produces a smaller force than the displacement generated by the thermal expansion of the three beams.

  The thermal actuator 50 shown in FIG. 5 produces a maximum force in the preferred direction of radial displacement 90, 92, 94, 96 because the beams 56, 60, 64, This is because current is applied to three of 68 at the same time. Since the radial motion 80, 82, 84, 86 is induced by applying current only to two adjacent beams, their radial potential forces are in the radial directions 90, 92, 94, 96. Smaller than. In another example, the displacement force generated in the radial direction 90 by applying current to the three beams 56, 60, 64 is greater than the force generated in the radial direction 90 due to thermal expansion of the beam 56 alone. Thus, the cross-sectional configuration of the beam can be designed to maximize force generation in a particular radial direction.

  6 and 7 show a second embodiment of a multi-directional thermal actuator 150 constructed on a substrate 152 according to the present invention. The multi-directional thermal actuator 150 of FIGS. 6 and 7 is substantially the same as the multi-directional thermal actuator 50 of FIG. 3 except that a centrally arranged beam 151 extending in a cantilever manner from the anchor 153 is added. Is different.

  The multi-directional thermal actuator 150 includes an anchor 154 having a first lower beam 156 extending from the anchor 154 in a cantilever manner and a second lower portion extending from the anchor 158 in a cantilever manner substantially parallel to the first lower beam 156. And an anchor 158 having a beam 160. The anchor 162 includes a first upper beam 164 extending therefrom in a cantilever manner and an anchor 166 having a second upper beam 168 extending in a cantilever manner substantially parallel to the first upper beam 164.

  The beam 151 can add structural support to the actuator 150 and / or provide a common connection to electrical ground, thereby supplying current to one or more of the beams 156, 160, 164, 168. In the illustrated embodiment, the beams 151 are arranged substantially symmetrically with respect to the beams 156, 160, 164, 168. In one embodiment, beam 151 is placed inside a rectangular space defined by beams 156, 160, 164, 168. The beams 151 can also be arranged asymmetrically with respect to the beams 156, 160, 164, 168.

  In the embodiment shown in FIG. 6, anchors 153, 154, 158, 162, 166, respectively, are used to deliver current and / or electrically ground one of beams 151, 156, 160, 164, 168, respectively. To connect to electrical traces 153A, 154A, 158A, 162A, 166A.

  Beams 151, 156, 160, 164, 168 are mechanically coupled at their distal ends by members 172. A via 170 is formed in the member 172 to mechanically couple the beams 151, 156, 160, 164, 168. Other structures can be used to mechanically couple the beam to the member. Two or more of the beams 151, 156, 160, 164, 168 can be electrically coupled to form a circuit. Alternatively, a ground tab can be used to connect one or more of the beams 156, 160, 164, 168 to the ground (see FIG. 4). In the inactive configuration, the beams 151, 156, 160, 164, 168 are substantially parallel to the surface of the substrate 152.

  In the illustrated embodiment, the beam 151 has a larger cross-sectional area to minimize current density and / or to add structural stability to the multi-directional thermal actuator 150. In one embodiment, the beam 151 is constructed of a material that has a lower electrical resistance than the material used to construct the beams 156, 160, 164, 168. In other embodiments, a conductive layer is provided on the beam 151 to reduce the current density compared to the current density of the beams 156, 160, 164, 168. As a result, the net expansion of beams 156, 160, 164, 168 for a given level of current is greater than the expansion of beam 151. That is, the beam 151 operates as a cold arm.

  In the illustrated embodiment, the beams 156, 160, 164, 168 have approximately equal cross-sectional areas. The beams 156, 160, 164, 168 are arranged in a generally rectangular configuration, as discussed with respect to FIGS. In an alternative embodiment, the arrangement of beams 156, 160, 164, 168 can be rotated with respect to beam 151 (see, eg, FIG. 8).

  A circuit can be formed by the cold arm 151, the member 172, and one or more of the beams 154, 160, 164, 168. A common cold arm 151 allows a current to be selectively applied to one or more of the beams 156, 160, 164, 168, thereby allowing the member 172 to be displaced in any radial direction. By applying current to any two adjacent beams 156, 160, 164, 168, the member 172 can be displaced in any of the radial directions 180, 182, 184, 186 as discussed above. . Due to the cross-sectional shape of the cold arm 151, the directions 180, 186 are preferred radial directions.

  The cold arm 151 can optionally include a flexure 202 formed in the vicinity of the reinforcing member 200 and / or the anchor 153. As used herein, “reinforcement member” refers to one or more ridges, bumps, grooves, or other structural features that increase resistance to curvature. The reinforcing member is preferably integral with the cold arm 151. In the illustrated embodiment, the reinforcing member 200 is a cantilever ridge that extends along a portion of the cold arm 151 (see FIG. 7), but is rectangular, square, triangular, or various other shapes. be able to. Further, the reinforcing member 200 can be positioned at the center of the cold arm 151 or along the edge thereof. It is also possible to use a plurality of reinforcing members.

  As used herein, “deflection” refers to depressions, depressions, holes, slots, cutouts, narrow, thin, or weak locations where the material is on an alternative material or other structure. Refers to a feature or material change that provides a controlled curvature at a particular location. As used herein, “controlled curvature” refers to a curvature that occurs primarily at discrete locations, rather than being distributed along the beam of a multi-directional thermal actuator. Controlled curvature is another mechanism that provides a preferred direction of radial displacement. Alternative materials suitable for use as deflection include polysilicon, metal, or polymeric materials. The flexure 202 comprises the most flexible section of the cold arm 151 and thus provides the position most likely to be bent during the operation of the multi-directional thermal actuator 150.

  The stiffness of the cold arm 151 compared to the stiffness of the flexure 202 and the beams 156, 160, 164, 168 determines the magnitude (direction and amount) of the curvature of the multi-directional thermal actuator 150 to a significant degree. In one embodiment, the reinforcing member 200 is used in combination with the flexure 202. In other embodiments, the reinforcing member 200 extends along a portion of the cold arm 151, but no deflection is used. The portion of the cold arm 151 without the reinforcing member 200 is the position of the controlled curve. In other alternative embodiments, the deflection 202 is formed in the cold arm 151 without the reinforcement member 200 so that the deflection 202 is in a controlled curvature position.

  FIG. 8 is a cross-sectional view of a thermal actuator 50A similar to FIG. 5 except that the orientation of the beams 56A, 60A, 64A, 68A is rotated 45 degrees. By applying a current to any two adjacent beams, it will be displaced in one of the radial directions 90, 92, 94, 96. Applying current to any three beams 56A, 60A, 64A, 68A results in radial displacement in one of the directions 80, 82, 84, 86.

  FIG. 9 is a cross-sectional view of three types of beams of the thermal actuator 210 similar to FIG. In the illustrated embodiment, the beams 212, 214, 216 are arranged symmetrically. By applying a current to one of the beams 212, 214, 216 (usually using the ground tab shown in FIG. 4), it will be displaced in one of the radial directions 220, 222, 224. Applying current to any two adjacent beams 212, 214, 216 will result in displacement in one of the radial directions 230, 232, 234. The beams 212, 214, 216 are arranged substantially symmetrically, but asymmetric types that emphasize displacement in one or more directions are also possible.

  FIG. 10 is a cross-sectional view of an alternative three beam type of thermal actuator 240 similar to FIG. The beams 242 244 246 are arranged asymmetrically. Beam 242 has a larger cross-sectional area (and therefore a smaller current density) than beams 244 and 246. By applying a current to one of the beams 242, 244, 246 (usually using the ground tab shown in FIG. 4), it will be displaced in one of the radial directions 250, 252, 254. By applying a current to two adjacent beams 246, 244, a displacement in radial direction 256 will occur.

  Due to the arrangement and geometry of the individual beams 242, 244, 246, the thermal actuator 240 has a preferred direction of displacement in direction 252 and a secondary less preferred direction of displacement in direction 250. This result is mainly due to the fact that the beam 242 curves more easily in the direction 252 than in the direction 250.

  FIG. 11 is a schematic diagram of an optical switch 350 that uses a 4 × 4 array of optical devices 352. As used herein, “optical device” refers to a reflector, lens, deflection device, waveguide, shutter, or engagement device. Each of the optical devices 352 is mechanically coupled to one or more multi-directional thermal actuators shown herein. In the in-plane position, the optical device 352 does not extend into the optical path of the input optical fibers 354a to 354d. In the out-of-plane configuration, the optical device 352 extends into the optical path of the input optical fibers 354a-354d. The array of vertical mirrors 352 optically couples the optical signal from any of the input fibers 354a-354d to any of the output fibers 356a-356d by selectively actuating a multi-directional thermal actuator. Arranged to allow. The optical switch 350 shown in FIG. 11 is merely an example. The multi-directional thermal actuator can be used in any of a variety of optical switch architectures, such as on / off switches (optical gates), 2 × 2 switches, 1 × n switches, or various other architectures It is. The optical device can be part of an optical communication system.

It is a side view of the thermal actuator before bending backward. FIG. 2 is a side view of the thermal actuator of FIG. 1 after being bent back. 1 is a plan view of a multidirectional thermal actuator according to the present invention. FIG. FIG. 4 is a side view of the multidirectional thermal actuator of FIG. 3. FIG. 4 is a cross-sectional view of the multidirectional thermal actuator of FIG. 3. FIG. 6 is a top view of an alternative multi-directional thermal actuator according to the present invention. It is sectional drawing of the multidirectional thermal actuator of FIG. FIG. 6 is a cross-sectional view of an alternative thermal actuator according to the present invention. It is sectional drawing of the 3 beam thermal actuator by this invention. 1 is a cross-sectional view of a three-beam asymmetric thermal actuator according to the present invention. 1 is a schematic view of an optical switch according to the present invention. FIG. 3 is a schematic diagram of an electrical trace connected to an anchor according to the present invention. FIG. 6 is a schematic diagram of an alternative electrical trace connected to an anchor according to the present invention.

Claims (46)

A multi-directional thermal actuator built on the surface of a substrate,
A first beam cantilevered from an anchor at a first end so as to extend substantially parallel to the surface of the substrate in an inactive state;
A second beam cantilevered from an anchor at a first end so as to extend substantially parallel to the surface of the substrate in an inactive state;
A third beam cantilevered from an anchor at a first end so as to extend substantially parallel to the surface of the substrate in an inactive state, the first beam, the second beam, and the The third beam is not coplanar,
A member that mechanically couples the distal ends of the first beam, the second beam, and the third beam;
A first circuit comprising at least the first beam, wherein the member is displaced in a first radial direction by applying a current to the first circuit;
A second circuit comprising at least the second beam, wherein the member is displaced in a second radial direction by applying a current to the second circuit;
A third circuit comprising at least the third beam, wherein the member is displaced in a third radial direction by applying a current to the third circuit;
A multi-directional thermal actuator.   The apparatus of claim 1, comprising a ground tab that electrically couples one or more of the first beam, the second beam, and the third beam to the substrate.   The apparatus of claim 1, comprising a resistor disposed between one or more of the beams and ground.   The apparatus of claim 1, wherein the first circuit comprises the first beam and the second beam.   The apparatus of claim 1, wherein the second circuit comprises the second beam and the third beam.   The apparatus of claim 1, wherein the third circuit comprises the third beam and the first beam.   The apparatus of claim 1, wherein the first beam and the ground tab comprise a fourth circuit, and the member is displaced in a fourth radial direction by applying a current to the fourth circuit.   The apparatus of claim 1, wherein the second beam and ground tab comprise a fifth circuit, and the member is displaced in a fifth radial direction by applying a current to the fifth circuit.   The apparatus of claim 1, wherein the third beam and the ground tab comprise a sixth circuit, and the member is displaced in a sixth radial direction by applying a current to the sixth circuit.   In a non-active state, at least a fourth beam cantilevered from an anchor at a first end so as to extend substantially parallel to the surface of the substrate, the fourth beam being mechanically coupled to the member The apparatus of claim 1. A seventh circuit comprising the first beam and the fourth beam, wherein the member is displaced in a seventh radial direction by applying a current to the seventh circuit;
An eighth circuit comprising the second beam and the fourth beam, wherein the member is displaced in the eighth radial direction by applying a current to the eighth circuit;
A ninth circuit comprising the third beam and the fourth beam, wherein the member is displaced in a ninth radial direction by applying a current to the ninth circuit;
The apparatus of claim 10, comprising:   The tenth circuit including the first beam, the second beam, and the third beam, wherein the member is displaced in the tenth radial direction when applied to the tenth circuit. The device described.   The tenth circuit comprises a third current density of the first beam and a fourth current density of the second beam smaller than the third current density, whereby the member is displaced in an eleventh radial direction; The apparatus according to claim 12.   The apparatus of claim 1, comprising a cold arm having a first end secured to a surface of the substrate and a distal end mechanically coupled to the member.   The apparatus of claim 1, comprising a cold arm having a first end secured to a surface of the substrate and a distal end mechanically and electrically coupled to the member.   The apparatus of claim 1, wherein the first beam, the second beam, and the third beam comprise a symmetric cross-sectional configuration.   The apparatus of claim 1, wherein the first beam, the second beam, and the third beam comprise an asymmetric cross-sectional configuration.   The apparatus of claim 10, wherein the first beam, the second beam, the third beam, and the fourth beam comprise a substantially rectangular cross-sectional configuration.   The apparatus of claim 1, comprising a plurality of multidirectional thermal actuators on the substrate. A multi-directional thermal actuator built on the surface of a substrate,
At least one beam is at least three beams that are not coplanar with the other two beams, each of the at least three beams extending substantially parallel to the surface of the substrate in an inactive state. At least three beams cantilevered from one or more anchors at the first end;
By mechanically applying a current to a circuit comprising a combination of any two or more of the at least three beams, the distal end of the beam is displaced in one of three or more non-parallel radial directions. A joining member;
A multi-directional thermal actuator. A multi-directional thermal actuator built on the surface of a substrate,
Four beams arranged in a generally rectangular cross-sectional configuration, each of the four beams extending from the one or more anchors at the first end so as to extend substantially parallel to the surface of the substrate. With four beams being cantilevered,
A member for mechanically coupling the distal end of the beam;
A multi-directional thermal actuator.   22. The two of the beams comprise upper beams, the two of the beams comprise lower beams, and the two upper beams are disposed above the two lower beams with respect to the surface of the substrate. Equipment.   23. The apparatus of claim 22, wherein the actuator is displaced vertically upward when a current is applied to the two lower beams.   23. The apparatus of claim 22, wherein the actuator is displaced vertically downward when a current is applied to the two upper beams.   23. The apparatus of claim 22, wherein the actuator is displaced horizontally when an electric current is applied to one of the lower beam and the upper beam disposed above the lower beam.   The apparatus of claim 21, wherein one of the beams is disposed above the other beam, and the two of the beams are laterally offset from each other.   The apparatus of claim 21, wherein the actuator is displaced both horizontally and vertically when a current is applied to any three of the beams.   A cold arm having a first end secured to the surface and a distal end attached to the member, wherein the cold arm is within the generally rectangular space defined by the beam. The apparatus of claim 21, wherein the apparatus is disposed substantially parallel to the beam.   22. A cold arm centered with respect to the beam, wherein the cold arm has a first end secured to the surface and a distal end connected to the member. The device described.   22. A cold arm disposed symmetrically with respect to the beam, wherein the cold arm has a first end secured to the surface and a distal end connected to the member. The device described.   24. The apparatus of claim 21, comprising a cold arm having a first end secured to the surface and a distal end attached to the member.   32. The apparatus of claim 31, comprising a deflection formed near the first end of the cold arm configured to provide a controlled curvature.   The flexure reduces recesses, depressions, cutouts, holes, locations where the material is narrow, thin or weak, alternative materials or other structural features, or resistance to bending at that location. 35. The apparatus of claim 32, comprising at least one of a material change.   32. The apparatus of claim 31, comprising a reinforcing member formed on the cold arm.   35. The apparatus of claim 34, wherein the reinforcing member is integrally formed with the cold arm.   32. The apparatus of claim 31, comprising a metal layer extending along the cold arm.   32. The apparatus of claim 31, wherein the cold arm is electrically isolated from the beam.   32. The apparatus of claim 31, wherein the beam and the cold arm comprise a circuit through which current flows.   32. The apparatus of claim 31, wherein the actuator is displaced both horizontally and vertically when a current is applied to a circuit comprising the cold arm and any one of the beams.   32. The apparatus of claim 31, wherein the actuator is displaced both horizontally and vertically when a current is applied to a circuit comprising the cold arm and any three of the beams.   32. The apparatus of claim 31, wherein the cold arm has a smaller current density than the beam at a given voltage.   The apparatus of claim 21, comprising a ground tab that electrically couples one or more of the beams to the substrate.   The apparatus of claim 21, comprising a plurality of multidirectional thermal actuators on the substrate.   The apparatus of claim 21, comprising at least one optical device mechanically coupled to the multidirectional thermal actuator.   45. The apparatus of claim 44, wherein the optical device comprises one of a reflector, a lens, a deflector, a waveguide, a shutter, or an engagement structure.   45. The apparatus of claim 44, comprising an optical communication system comprising at least one optical device.

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